The 72-year-old from Colwyn Bay also spoke of his sadness that the late Hollywood funnyman’s turn in his forthcoming sci-fi caper Absolutely Anything would be the last time fans would be able to enjoy his on-screen talents.

National treasure Jones, who shot to global fame in the BBC’s surreal Flying Circus series in the late ’60s, said he got the idea to cast Williams, who committed suicide last week after a long-battle with depression, after bumping into him at an awards ceremony back in 2010.

Monty Python star Terry Jones

“My son Bill had co-directed a documentary called Monty Python: Almost The Truth (The Lawyer’s Cut) which had been nominated for an Emmy” – US TV’s version of the Oscars – “so the pair of us flew over to Los Angeles,” he said.

“When we got there I spotted Robin sitting in the front row, and, as we’d met a few times before, I went over to re-introduce myself and ask if he’d like to play the voice of talking dog called Dennis in a new film I was working on.

“He told me to send him a script and, after he’d given it the once over, he got back to me and said, ‘Great, let’s get this made now’.

“It was a simple as that, really.”

Nothing is ever really simple in the world of movie-making, however, Jones adding that it took a further four years to raise the finances to start shooting the flick, in which Simon Pegg plays a put-upon teacher suddenly granted unlimited God-like powers by a troupe of visiting aliens – CGI ETs voiced by the Welshman’s fellow Pythons Michael Palin, John Cleese and Terry Gilliam.

“And one of the first things Simon’s character does with his new found abilities is to grant his pet the gift of speech – not that he much likes what Dennis has to say from himself,” laughed Jones, who added that it took perfectionist Williams the separate goes to really nail the part.

“The first time was a over a Skype call from LA, which we had to abandon because the connection was really bad and there was this interminable 10 second delay every time Robin said anything.

“The second time Bill and I went over to record him near his home in San Francisco, but Robin still wasn’t satisfied with his performance.

“But then he rang me on my mobile one day and went, ‘Terry, I’ve got an idea – I’m going to play Dennis as though he’s a 16-year-old kid’.

“After that he came over to London and we did it all there.

“He was just brilliant and will really steal the show when the movie finally comes out next spring.”

Although Jones added that he found the Oscar winner – Williams picked up an Academy Award for his part in Good Will Hunting – was far removed from the manic ad-libber famed for his wild voice-over roles in hit films like Disney’s 1992 take on classic Middle Eastern folk tale Aladdin.

“He was just a sweet, very humble man who was a complete dream to work with – it’s such a shame he’s gone,” said the Life of Brian director, who confessed to having been a big fan of his more serious roles.

“Good Morning Vietnam was such a good film and a real favourite of mine, as was Dead Poets’ Society” – in which Williams played an unorthodox English teacher railing against the starchy traditions of a conservative boarding school – “He was really wonderful in that.

“It’s so sad to think that my film, once it comes out, will probably be the last thing anyone will see him do.”

And Jones wasn’t the only Python Williams had worked with during his long eclectic career, having collaborated with Eric Idle on The Tale of the Frog Prince for US TV and starred in two Terry Gilliam movies, namely The Adventures of Baron Munchausen and The Fisher King, for which the comedian won a Golden Globe for his acting.

Neither was Jones the only Python paying tribute, Gilliam adding in his own inimitable style that Williams – who’d discovered he had Parkinson’s disease prior to taking his own life – had been “the most astonishingly funny, brilliant, profound and silly miracle of mind and spirit.

“He was a giant heart, a fireball friend and a wondrous gift from the gods.

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